Climate change is projected to result in severe and widespread droughts within the next 30-90 years. Water scarcity is expected to affect 48% of the global population by 2025, and result in depletion of 90% of available freshwater sources. This projected demand for freshwater requires the development and adoption of increasingly energy-efficient and affordable desalination technologies, which are currently energy intensive. Seawater desalination processes require thermal, hydraulic, or electrical energy to separate feed water, typically 35 ppt (parts per thousand) total dissolved solids (TDS) into desalinated water (TDS<0.5 ppt) and brine. The current state-of-the-art in desalination, seawater reverse osmosis (SWRO), requires large capital investments and incurs high operating costs, resulting in water that is expensive (>$0.53 m−3) to produce. Furthermore, the specific energy consumption and desalination cost escalates with increasing feed salinity due to increased osmotic pressure. SWRO is uneconomical at salinities greater than 60 ppt due to the low recovery ratio and high specific energy consumption (7 Wh at 60 ppt). Moreover, beyond at least 80 ppt TDS, reverse osmosis becomes physically impossible since the osmotic pressure is greater than the membrane burst pressure (e.g., 69 bar). For this reason, thermal processes such as multi-stage flash distillation or multiple-effect distillation ($0.52-1.75 m−3) are more economical, in areas such the Gulf Cooperation Council countries, because of the high water salinity (up to 60 ppt near land). Consequently, nearly 80% of Gulf desalination capacity, which accounts for more than half of worldwide seawater desalination capacity, is provided using energetically-intensive thermal processes (e.g., >20 Wh L−1). Described herein are systems and processes that reduce both energy consumption and overall costs for desalination using a reversible electrochemical battery.